<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    .one {
      width: 200px;
      height: 200px;
      background-color: pink;
      transition: all .3s;
    }

    .two {
      transform: rotate(720deg);
    }
  </style>
  <script src="jquery.min.js"></script>
</head>

<body>
  <div class="one two"></div>
  <script>
    // let one = document.querySelector('.one')
    // one.className = "two"  // // <div class="two"></div> 会直接进行覆盖式修改
    $(".two").addClass("one") // <div class="one two"></div> 只会对指定类有修改
    $(".two").removeClass("one") // <div class="two"></div> 只会对指定类有修改

  </script>
</body>

</html>